PIEZOELECTRIC AND OTHER TYPES OF MICROPHONES
Microphones can be classified in terms of how they create an electrical signal:

• Electromagnetic: Ribbons (thin metal ribbon suspended between magnets), dynamic (moving coil)
  
  
  
• Electrostatic: condensers, electrets, etc.
  
  
• Piezoelectric: based on variations of electric resistance of their sensor induced by changes in sound pressure. Carbon button microphones (old AT&T handsets) and desktop "far-field" microphones are popular examples of these. Lower sensitivity, more distortion, and non-flat frequency responses are characteristics of these microphones.